The surgical method of donor removal in Hair Restoration Surgery (HRS) rests on the principal of “donor dominance”: the idea that hair from the “donor area”, the region of the scalp in which the hair is destined to remain, will continue to grow in the same fashion even when transplanted to the “recipient area”, the scalp zone of non-permanent hair growth.
Beginning around the 1950s, large punch grafts were excised from the donor area and transplanted to the recipient area. Utilization of these large grafts was necessary to ensure hair survival after transplantation. Smaller grafts, or implantation into smaller recipient sites, were not yet feasible due to the low graft viability secondary to decreased blood perfusion of transplanted grafts. While this large-graft method enabled transplanted graft growth in the recipient area, the grafts often had a “pluggy” appearance and the punched-out scars in the donor area left an unattractive buckshot pattern in the back of a patient's head.
To address these shortcomings of original HRS techniques, an alternative to donor hair harvesting in the form of a strip technique was proposed. This approach involved removing a strip of hair-follicle bearing skin from the donor region, suturing the donor wound closed, dissecting out each individual follicle or cluster of follicles (a.k.a. follicular unit (FU)), and transplanting each individual FU separately in the recipient area. This approach, coined “micrografting” or follicular unit transplanting (FUT), helped minimize the “pluggy” appearance of large grafts in the recipient area and left only a linear scar in the donor area rather than a more-obvious buckshot pattern.
Motivated by a desire to obtain the largest number of grafts via the “micrografting” technique, many patients pushed for wider donor strip removal and were subsequently left with relatively large (2-10 mm) linear scars in the occipital (back) portion of their head. This obvious telltale sign of the surgery provided impetus for the development of follicular unit extraction (FUE). In FUE each individual follicular unit is meticulously punched out from the donor area with a small biopsy punch and transplanted into the recipient area. This differs from the original approach to HRS in that FUE involves the transfer of only individual FUs rather than large (4-5 mm) punch grafts. This novel technique eliminated the stigma of a linear scar in the donor area and, when done properly, minimized the appearance of a buckshot pattern in the donor area. However, several disadvantages persisted with the advent of FUE: a high percentage (up to 40%) of hairs are transected (thus, limiting their survival), a moth-eaten scarring pattern often remains from where FUs are extracted, and a considerable number of patients (up to 30%) are not candidates for FUE based on their hair characteristics (e.g. light color or considerable curl) that present undue challenges for the surgeon.